Study of Aerodynamic Interactions of Dual Flapping Airfoils in Tandem Configurations

2012 ◽  
Vol 160 ◽  
pp. 301-306
Author(s):  
Bao Li Zhu ◽  
Hui Pen Wu ◽  
Tian Hang Xiao
Keyword(s):  
Viscous Flow ◽  
Great Influence ◽  
Aerodynamic Performance ◽  
Navier Stokes ◽  
Propulsive Efficiency ◽  
Motion Models ◽  
Hybrid Meshes ◽  
Thrust Generation ◽  
Unsteady Viscous Flow ◽  
Flapping Airfoil

The unsteady viscous flow fields of dual flapping airfoils in tandem configurations are simulated by a Navier-Stokes Solver based on dynamic deformable hybrid meshes. Aerodynamic interactions of three motion models are studied including flapping fore airfoil with fixed aft airfoil, two airfoils flapping in phase and out-of-phase. The results indicate that the aft airfoil in the wake of the flapping fore airfoil has great influence on the aerodynamic performance. When the fore airfoil flaps with a fixed aft airfoil, the thrust generation and thrust propulsive efficiency were enhanced by 65% and 44% respectively, compared to that of single flapping airfoil. When the two airfoils stoke in phase, the thrust generation is twice over that of single flapping airfoil. However the out-of-phase stroking has relatively much lower thrust.

URANS Studies of Effect of Eccentricity on Ship–Lock Interactions

2016 ◽  
Vol 13 (04) ◽  
pp. 1641012
Author(s):  
Qingjie Meng ◽  
Decheng Wan
Keyword(s):  
Viscous Flow ◽  
Hydrodynamic Interaction ◽  
Vertical Displacement ◽  
Navier Stokes ◽  
Test Case ◽  
The Third ◽  
Surface Pressure Distribution ◽  
Sst Turbulence Model ◽  
Unsteady Viscous Flow ◽  
Ship Lock

The unsteady viscous flow around a 12000TEU ship model entering the Third Set of Panama Locks with different eccentricity is simulated by solving the unsteady Reynolds averaged Navier–Stokes (RANS) equations in combination with the [Formula: see text]SST turbulence model. Overset grid technology is utilized to maintain grid orthogonality and the effects of the free surface are taken into account. The hydrodynamic forces, vertical displacement as well as surface pressure distribution are predicted and analyzed. First, a benchmark test case is designed to validate the capability of the present methods in the prediction of the viscous flow around the ship when maneuvering into the lock. The accumulation of water in front of the ship during entry into a lock is noticed. A set of systematic computations with different eccentricity are then carried out to examine the effect of eccentricity on the ship–lock hydrodynamic interaction.

Numerical Study on Thrust Generation Performance of Plunging Airfoils

2013 ◽  
Vol 312 ◽  
pp. 235-238
Author(s):  
Ji Gao ◽  
Rui Shan Yuan ◽  
Ming Hui Zhang ◽  
Yong Hui Xie
Keyword(s):  
Viscous Flow ◽  
Numerical Study ◽  
Angle Of Attack ◽  
Leading Edge ◽  
Thrust Coefficient ◽  
Propulsive Efficiency ◽  
Propulsion Performance ◽  
Incompressible Viscous Flow ◽  
Thrust Generation ◽  
The Difference

In this paper, the effects of angle of attack, camber and camber location on propulsion performance of flapping airfoils undergoing plunging motion were numerically studied at Re=20000 and h=0.175. The unsteady incompressible viscous flow around four different airfoil sections was simulated applying the dynamic mesh. The results show that the time averaged thrust coefficient CTmean and propulsive efficiency η of the symmetric airfoil decrease with the increasing angle of attack, and the variation of CTmean is more obvious than that of CPmean. Both CTmean and η for NACA airfoils studied in this paper decrease with the increasing camber and the difference between the propulsion performances of different airfoils is not obvious, and the thrust generation and power of various NACA airfoils gradually increase during the downstroke and decrease during the upstroke. Under the same conditions, the airfoil with a further distance between the maximum camber location and the chord of the leading edge leads to higher propulsive efficiency.

scholarly journals Optimization of Flapping Airfoils for Maximum Thrust and Propulsive Efficiency

10.14311/508 ◽  
2004 ◽  
Vol 44 (1) ◽  
Author(s):  
I. H. Tuncer ◽  
M. Kay
Keyword(s):  
Large Scale ◽  
High Efficiency ◽  
Leading Edge ◽  
Laminar Flows ◽  
Navier Stokes ◽  
Propulsive Efficiency ◽  
Thrust Generation ◽  
Optimization Function ◽  
Optimization Parameters ◽  
Large Scale Vortex

A numerical optimization algorithm based on the steepest decent along the variation of the optimization function is implemented for maximizing the thrust and/or propulsive efficiency of a single flapping airfoil. Unsteady, low speed laminar flows are computed using a Navier-Stokes solver on moving overset grids. The flapping motion of the airfoil is described by a combined sinusoidal plunge and pitching motion. Optimization parameters are taken to be the amplitudes of the plunge and pitching motions, and the phase shift between them. Computations are performed in parallel in a work station cluster. The numerical simulations show that high thrust values may be obtained at the expense of reduced efficiency. For high efficiency in thrust generation, the induced angle of attack of the airfoil is reduced and large scale vortex formations at the leading edge are prevented. 

Time-Accurate Analysis of the Viscous Flow Around Puller Podded Drive Using Sliding Mesh Method

2014 ◽  
Vol 137 (1) ◽  
Author(s):  
Reza Shamsi ◽  
Hassan Ghassemi
Keyword(s):  
Experimental Data ◽  
Viscous Flow ◽  
Computational Method ◽  
Navier Stokes ◽  
Percentage Error ◽  
Accurate Analysis ◽  
Sliding Mesh ◽  
Mesh Method ◽  
Unsteady Viscous Flow ◽  
Thrust And Torque

In this paper a computational method is presented for predicting the unsteady hydrodynamic forces acting on podded drive components. These numerical simulations are performed with the aim of accurately studying the interaction between the propeller, the pod, and the strut. In order to simulate the unsteady viscous flow around a puller type podded drive, a Reynolds-Averaged Navier–Stokes (RANS) solver is used. The time-accurate calculations are made by applying the sliding mesh method. Structured and unstructured mesh techniques are used for the propeller and podded drive. The method is applied in the case of the straight condition. The unsteady propeller thrust and torque coefficient fluctuations are predicted for advance velocity ratios ranging from 0.2 to 1.0. The time averaged forces of the podded drive obtained by an unsteady analysis are compared to and verified by the steady result and the experimental data. Finally, discrepancies between the simulation results and the experimental data have been quantitatively evaluated in terms of the relative percentage error for the propulsive characteristics.

scholarly journals Numerical Investigation of the Effects of Nonsinusoidal Motion Trajectory on the Propulsion Mechanisms of a Flapping Airfoil

2019 ◽  
Vol 141 (4) ◽  
Author(s):  
A. Boudis ◽  
A. C. Bayeul-Lainé ◽  
A. Benzaoui ◽  
H. Oualli ◽  
O. Guerri ◽  
...  
Keyword(s):  
Thrust Force ◽  
Major Effect ◽  
Navier Stokes ◽  
Improve Performance ◽  
Navier Stokes Equation ◽  
Propulsive Efficiency ◽  
Flow Vorticity ◽  
Naca0012 Airfoil ◽  
Flapping Airfoil ◽  
Incompressible Navier Stokes Equation

The effect of nonsinusoidal trajectory on the propulsive performances and the vortex shedding process behind a flapping airfoil is investigated in this study. A movement of a rigid NACA0012 airfoil undergoing a combined heaving and pitching motions at low Reynolds number (Re = 11,000) is considered. An elliptic function with an adjustable parameter S (flattening parameter) is used to realize various nonsinusoidal trajectories of both motions. The two-dimensional (2D) unsteady and incompressible Navier–Stokes equation governing the flow over the flapping airfoil are resolved using the commercial software starccm+. It is shown that the nonsinusoidal flapping motion has a major effect on the propulsive performances of the flapping airfoil. Although the maximum propulsive efficiency is always achievable with sinusoidal trajectories, nonsinusoidal trajectories are found to considerably improve performance: a 110% increase of the thrust force was obtained in the best studied case. This improvement is mainly related to the modification of the heaving motion, more specifically the increase of the heaving speed at maximum pitching angle of the foil. The analysis of the flow vorticity and wake structure also enables to explain the drop of the propulsive efficiency for nonsinusoidal trajectories.

Effects of stator splitter blades on aerodynamic performance of a single-stage transonic axial compressor

2020 ◽  
Vol 14 (4) ◽  
pp. 7369-7378
Author(s):  
Ky-Quang Pham ◽  
Xuan-Truong Le ◽  
Cong-Truong Dinh
Keyword(s):  
Stokes Equations ◽  
Three Dimensional ◽  
Axial Compressor ◽  
Aerodynamic Performance ◽  
Numerical Results ◽  
Single Stage ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Operating Stability ◽  
Length Coverage

Splitter blades located between stator blades in a single-stage axial compressor were proposed and investigated in this work to find their effects on aerodynamic performance and operating stability. Aerodynamic performance of the compressor was evaluated using three-dimensional Reynolds-averaged Navier-Stokes equations using the k-e turbulence model with a scalable wall function. The numerical results for the typical performance parameters without stator splitter blades were validated in comparison with experimental data. The numerical results of a parametric study using four geometric parameters (chord length, coverage angle, height and position) of the stator splitter blades showed that the operational stability of the single-stage axial compressor enhances remarkably using the stator splitter blades. The splitters were effective in suppressing flow separation in the stator domain of the compressor at near-stall condition which affects considerably the aerodynamic performance of the compressor.

Reduced-Order Modeling of Unsteady Viscous Flow in a Compressor Cascade

AIAA Journal ◽  
10.2514/2.477 ◽  
1998 ◽  
Vol 36 (6) ◽  
pp. 1039-1048 ◽  
Author(s):  
Razvan Florea ◽  
Kenneth C. Hall ◽  
Paul G. A. Cizmas
Keyword(s):  
Viscous Flow ◽  
Reduced Order Modeling ◽  
Compressor Cascade ◽  
Reduced Order ◽  
Unsteady Viscous Flow
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